WASHINGTON (CNN) -- John McCain and Rudy Giuliani are tied among Republican voters in New Hampshire, with Mitt Romney in third place and Newt Gingrich showing scant support, a poll released Wednesday said.

The CNN/WMUR New Hampshire presidential primary poll conducted by the University of New Hampshire was carried out March 27 - April 3. The poll's margin of error was plus or minus 5.5 percentage points.

Of the New Hampshire Republicans polled, 29 percent supported McCain and 29 percent backed Giuliani. In February, only one point separated the senator from Arizona from the former mayor of New York City. (Read the complete poll results -- PDF)

The latest poll found Romney, the former governor of Massachusetts, supported by 17 percent; former Sen. Fred Thompson of Tennessee, 3 percent; and former Speaker of the House Newt Gingrich, 2 percent.

Fourteen percent described themselves as undecided.

Growing divide between moderates, conservatives

The poll points to what appears to be a growing gulf between moderates and conservatives in the Granite State.

Among people who identified themselves as conservative GOP primary voters, Romney and Giuliani are tied for the lead -- at 24 percent each.

Romney's gains among conservatives appear to have come at Giuliani's expense. The Massachusetts governor gained 11 points among conservatives, while Giuliani lost 7 points.

But Giuliani is still tied for first overall because he gained 11 points among moderate GOP primary voters.

In February, most of Giuliani's support came from conservatives; most of his current support comes from moderates. Meanwhile, McCain's favorable ratings shot up 15 points among conservatives.

Little support for Thompson, Gingrich

Two other potential GOP candidates appear to have made little impact among state voters: Nearly half of GOP primary voters said they have an unfavorable view of former speaker Newt Gingrich, and his potential share of the vote has plummeted from 9 percent in February to his current 2 percent.

Thompson won just 3 percent support among New Hampshire primary voters, though that may be related to the fact that he has yet to announce that he is officially in the race.

The telephone poll questioned 306 state residents who say they will vote in the Republican primary. When the sample was broken into conservative and moderates, the sampling error increased from plus or minus 5.5 percentage points to plus or minus 8 points.

Iraq top issue for Republicans

Iraq emerged as the single biggest issue of concern to GOP primary voters, with 29 percent identifying it as such. It was followed by the economy (13 percent); health care (9 percent); foreign policy (6 percent); and immigration (5 percent).

Romney's religion was deemed a concern to few voters: 4 percent said the fact that he is a Mormon would make them more likely to vote for him; 10 percent said it would make them more likely to vote against him; and 86 percent said it would have no impact on their vote.

One percent of voters said McCain's age, 70, would make them more likely to vote for him; 19 percent said it would make them less likely to do so; and 78 percent said it would have no impact.